<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Work on this issue](https://contributors.gitlab.com/manage-issue?action=work&projectId=278964&issueIid=287770) - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=287770) </details> <!--IssueSummary end--> This is related to Issue > https://gitlab.com/gitlab-org/gitlab/-/issues/267751. Please see the comment > https://gitlab.com/gitlab-org/gitlab/-/issues/267751#note_453228166 Here's an instance where it'd be so nice if we could add extra class on the Flash partial file `app/views/layouts/_flash.html.haml`. | Inline View | Side-by-side View | | ------ | ------ | |  |  | To fix this, we had to add some new CSS styles > MR https://gitlab.com/gitlab-org/gitlab/-/merge_requests/48439. This is not ideal, because we prefer using [utility class](https://docs.gitlab.com/ee/development/fe_guide/style/scss.html#utility-classes) instead of adding new CSS. And in this situation, we can definitely use our utility class to solve this. ## Proposal In `app/views/projects/commit/show.html.haml`, we have access to an instance variable [`@content-class`](https://gitlab.com/gitlab-org/gitlab/blob/20fa0acb012a819861053effc5c26378ed8b6e7d/app/views/projects/commit/show.html.haml#L7) for us to add additional class to the content. It would be nice if we could do the same for our Flash container; for instance `@extra-flash-class: 'gl-mx-auto'`.